1. Field of the Invention
This invention relates to a water-in-oil type emulsion explosive envelope, and more particularly to a water-in-oil type emulsion explosive envelope which prevents the folding or bending of the envelope, loosening of a wrapping paper and the like.
2. Related Art Statement
Since the water-in-oil type (hereinafter abbreviated as W/O type) emulsion explosives contain water, they are high in the safeness as compared with the conventional dynamite and also tend to enhance performances as compared with a slurry explosive containing water, so that they are widely used.
As a wrapping material in the conventional W/O type emulsion explosive envelopes, there were used coated papers such as waxed laminate paper obtained by laminating an extrusion polyethylene film onto a surface of a paper as a substrate and a paraffin coating on the other surface thereof, double-laminated paper obtained by laminating extrusion polyethylene films on both surfaces of the paper and the like. These coated papers were used by wrapping the paper double by means of a cylinder forming machine.
An example of the latter case will be described with reference to the accompanying drawing.
In FIG. 3 is shown a sectional view of a part of the wrapped paper in the conventional W/O type emulsion explosive envelope.
This example shows the use of a coated paper obtained by laminating an extrusion polyethylene film 4 on each surface of a paper 5 and wrapping it double.
Since such a conventional coated paper is used, the W/O type emulsion explosive envelope is excellent in the humidity resistance.
However, the conventional W/O type emulsion explosive envelopes have problems that the folding or bending as well as the loosening of the wrapped paper are caused though the humidity resistance is excellent. Particularly, there is caused a problem that the wrapped paper is loosened in a water springing portion at an explosive inserting and blasting site. It is needless to say that the insertion of the explosive envelope into the blasting hole is obstructed when the explosive envelope is folded or bent.